Guidelines for the Conversion of Urban Four-Lane Undivided Roadways to Three-Lane Two-Way Left-Turn Lane Facilities.

摘要

The purpose of this project was to investigate the impacts and factors related to the feasibility of urban four-lane undivided to three-lane cross section conversions. Past research and case study experiences (in Iowa and the United States) are documented, and factors related to the feasibility of converting a four-lane undivided roadway to a three-lane cross section (see Figure 2) are also identified and discussed. The focus of this report is limited to the discussion of one possible mitigation measure (i.e., a three-lane cross section) for urban four-lane undivided roadways being considered for a cross section improvement. In other words, the operation and/or safety conditions along a particular urban four-lane undivided roadway have degraded enough that several different cross section improvements are being evaluated. This report provides guidelines to assist transportation professionals in their consideration of the four-lane undivided to three-lane conversion alternative. Factors that should be considered for conversion feasibility are identified and their characteristics discussed.